title: Long-term exposure to black carbon and carotid intima-media thickness: the normative aging study.
abstract: BACKGROUND
  Evidence suggests that air pollution is associated with atherosclerosis and that traffic-related particles are a particularly important contributor to the association.
  
  
  OBJECTIVE
  We investigated the association between long-term exposure to black carbon, a correlate of traffic particles, and intima-media thickness of the common carotid artery (CIMT) in elderly men residing in the greater Boston, Massachusetts, area.
  
  
  METHODS
  We estimated 1-year average exposures to black carbon at the home addresses of Normative Aging Study participants before their first CIMT measurement. The association between estimated black carbon levels and CIMT was estimated using mixed effects models to account for repeated outcome measures. In secondary analyses, we examined whether living close to a major road or average daily traffic within 100 m of residence was associated with CIMT.
  
  
  RESULTS
  There were 380 participants (97% self-reported white race) with an initial visit between 2004 and 2008. Two or three follow-up CIMT measurements 1.5 years apart were available for 340 (89%) and 260 (68%) men, respectively. At first examination, the average ± SD age was 76 ± 6.4 years and the mean ± SD CIMT was 0.99 ± 0.18 mm. A one-interquartile range increase in 1-year average black carbon (0.26 µg/m3) was associated with a 1.1% higher CIMT (95% CI: 0.4, 1.7%) based on a fully adjusted model.
  
  
  CONCLUSIONS
  Annual mean black carbon concentration based on spatially resolved exposure estimates was associated with CIMT in a population of elderly men. These findings support an association between long-term air pollution exposure and atherosclerosis.
authors.affiliation: Cardiovascular Epidemiology Research Unit, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA. ewilker@bidmc.harvard.edu
authors.forename: Elissa H
authors.initials: EH
authors.lastname: Wilker
authors.forename: Murray A
authors.initials: MA
authors.lastname: Mittleman
authors.forename: Brent A
authors.initials: BA
authors.lastname: Coull
authors.forename: Alexandros
authors.initials: A
authors.lastname: Gryparis
authors.forename: Michiel L
authors.initials: ML
authors.lastname: Bots
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: David
authors.initials: D
authors.lastname: Sparrow
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001900:Boston / Q000453:epidemiology; D002244:Carbon / Q000032:analysis* / Q000633:toxicity; D059168:Carotid Intima-Media Thickness / Q000706:statistics & numerical data*; D015331:Cohort Studies; D004781:Environmental Exposure / Q000009:adverse effects*; D040362:Geographic Information Systems; D006801:Humans; D008297:Male; D015233:Models, Statistical; D001335:Vehicle Emissions / Q000032:analysis* / Q000633:toxicity
chemical_list: D001335:Vehicle Emissions; D002244:Carbon